JPS62178356A - Printing hammer drive circuit - Google Patents

Abstract

PURPOSE:To obtain a printing hammer drive circuit capable of accelerating printing operation by providing a plurality of piezoelectric elements which generates an expansion force through a drive voltage to drive a flight hammer, discharges an electric charge accumulated by a discharging circuit to cause a contraction action and reduces an impact force when the flight hammer is returned to an original position. CONSTITUTION:A drive voltage is increased, a piezoelectric element 3 is increasingly expanded, the tip of the piezoelectric element 3 and a flight hammer 4 are accelerated and the flight hammer 4 is separated from the piezoelectric element 3 flying. A printing wire 41 runs into a platen 7, printing dots. After the elapse of a certain time from the starting of a printing gate signal, a discharge gate signal is output to turn ON a transistor Q2 of a switching element, and thereby an electric charge accumulated in the piezoelectric element 3 is discharged through a resistor R2. The piezoelectric element 3 contracts and the flight hammer 4 hits while the tip of the piezoelectric element is undergoing a reduction in displacement. Since it is possible to reduce the relative speed of the piezoelectric element 3 and the flight hammer 4, the recoiling of the flight hammer 4 is lessened and is quickly restored to a standstill. As a result, a time required until a next printing action is commenced can be shortened and printing be accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing hammer drive circuit, and particularly to a printing hammer drive circuit for a dot impact type printer using a piezoelectric element.

[Conventional technology]

Conventionally, electromagnetic type printing hammer driving circuits have been widely used as printing hammer driving circuits for dot impact printers. However, electromagnetic printing hammer drive circuits generate a magnetic field by energizing a coil, and use that magnetic force to drive the printing hammer, so they require a large amount of input energy and have problems such as heat generation and magnetic interference. there were.

Therefore, in recent years, a printing hammer drive circuit using a piezoelectric element that has good electrical/mechanical energy conversion efficiency, low power consumption, low heat generation, and no magnetic interference has been developed. Reported by C84-49.

FIG. 3 is a schematic diagram for explaining the operation of an example of a conventional printing hammer drive circuit according to the above-mentioned document.

The printing hammer of this example has a fly I supported by a leaf spring 42 at the tip of the piezoelectric element 3 in the direction of extension (direction of arrow F).
・Hammer 4 is arranged so that it is in contact with each other) The structure has a plurality of grooves. For fly I/hammer 4,
A printing wire 41 is provided for printing character dots.

This printing hammer drive circuit includes Goo 1 to signal generation circuit 1a.
When the switching element of the switch circuit 2a is made conductive by the printing gate signal Sc from the 1000 MHz signal Sc, and the drive voltage ■c is applied to the piezoelectric element 3, the flight hammer 4 transfers the stretching force caused by the high-speed stretching operation of the piezoelectric element 3 to the piezoelectric element. It is driven and accelerated by the piezoelectric element 3 and flies away from the piezoelectric element 3. Then, the printing wire 41 collides with the platen 7 via the ink ribbon 5 and the printing paper 6 located in front, and the characters ``-'' are printed on the printing paper 6.

Thereafter, the flight hammer 4 returns to the piezoelectric element 3 due to the repulsive force from the platen 7 and the restoring force of the leaf spring 42. At this time, the charge accumulated in the piezoelectric element 3 passes through the discharge circuit formed by the switching element of the switch circuit 2a being turned on by the discharge gate signal SD, and the discharge is completed, and the piezoelectric element 3 returns to its original size. Since the fly 1 and the hammer 4 have returned, they collide with the piezoelectric element 3, bounce back, and return again due to the restoring force of the leaf spring 42. This process is repeated several times, and then the fly 1 and the hammer 4 are statically fixed.

FIG. 4 is a waveform diagram showing the signal waveform of the conventional example shown in FIG. 3, the displacement of the flight hammer 4 and the tip of the piezoelectric element 3, and the elapse of three hours.

From FIG. 11, it can be seen that it takes about 2 mS for the flight hammer 4 to stabilize after the flight hammer 4 starts flying. The amount of displacement generated by the piezoelectric element 3 itself is 10~
20 ), t m , so even if the drive voltage VC is applied to the piezoelectric element 3 during this approximately 2 n1S, it is hardly possible to drive the flight hammer 4 . therefore,
The next drive of the flight hammer 4 is started after approximately 2 ms has elapsed until the bounce settles down.

Note that the dotted line portion of the waveform of the displacement of the tip of the piezoelectric element shown in FIG. 4 is the waveform when no switch element is used in the discharge circuit. In this case, the discharging resistance of the discharging circuit needs to be larger than when using the Swiss-Sochi element, so it takes time for the discharge to occur, resulting in an elongated waveform as shown by the dotted line. The operation of the flight hammer 4 in this case is similar to the operation described above.

[Problem that the invention seeks to solve]

In the above-mentioned conventional printing hammer drive circuit, the hammer returns after printing dots and collides with the piezoelectric element and bounces. It takes a long time for the hammer to settle down. There was a problem that the fE opening was delayed and printing speed could not be increased.

An object of the present invention is to provide a printing hammer drive circuit that can speed up printing.

To solve this problem, the printing hammer driving circuit of the present invention is selectively driven according to the pattern of the pressed characters. a gate signal generation circuit that outputs a printing gate signal for the printing and a discharge gate I signal generated at the timing when the driven flight hammer returns to its original position; a plurality of switch circuits that output a drive voltage and conduct a second switch element by the discharge gate signal to form a discharge circuit; and a plurality of switch circuits that generate an extension force by the drive voltage to drive the flight hammer, and the discharge circuit The flight hammer has a plurality of piezoelectric elements that reduce the impact force when the flight hammer returns to its original position by discharging the accumulated charge and reducing the size of the flight hammer.

[Effect]

When a driving voltage is applied to the piezoelectric element, the piezoelectric element causes a high-speed elongation motion, and the flight hammer in contact with the piezoelectric element is driven by the elongation force of the piezoelectric element.

It is accelerated and flies away from the piezoelectric element, and the printing wire provided on the flight hammer collides with the platen to print the driver I.

On the other hand, since a piezoelectric element is a capacitive element, when a voltage is applied, charge is accumulated, and unless it is forcibly discharged, the charge only decreases little by little due to natural discharge, so the displacement of the piezoelectric element is determined by the driving voltage. After the rise immediately after application, the displacement remains almost constant.

Furthermore, when the charges accumulated in the piezoelectric element are discharged through a resistor, the displacement of the tip of the piezoelectric element also decreases exponentially.

Therefore, in the present invention, after applying a driving voltage to the piezoelectric element,
After a certain period of time has elapsed, that is, at the timing when the printing wire collides with the platen and the flight hammer returns to the piezoelectric element, the electric charge accumulated in the piezoelectric element is discharged through the resistor, thereby causing the piezoelectric element to become common. Since the fly I hammer collides with the piezoelectric element while the displacement of the end is decreasing, the relative speed between the two becomes small, the rebound of the flight hammer is reduced, and it can be quickly stabilized.

As a result, the time required to start the next printing operation can be shortened, and printing can be performed faster.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram including one embodiment of the present invention.

In this embodiment, the gate I/signal generating circuit 1, P
A printing gate signal Sc is outputted to selectively drive the i number of flight hammers 4 according to the character pattern. The Sui-Sochi circuit 2 uses this print gate signal Sc
is input, the switching element transistor Q1 is turned on, and the power supply V is turned on. A driving voltage VC is applied to the piezoelectric element 3 through a resistor R1.

The piezoelectric element 3 expands in response to the drive voltage VC, generates an expansion force, and drives the flight hammer 4. Next, at the timing when the flight hammer 4 returns to its original position after printing dots, a discharge gate signal SD is output from the gate signal generation circuit 1, and this discharge gate signal So causes the switching circuit 2 to The transistor Q2 is turned on, and the electric charge accumulated in the piezoelectric element 3 is discharged via the resistor R2.

Note that FIG. 1 shows a plurality of switch circuits 2. Piezoelectric element 3
and Fly I Hammer 4, only one system is shown.

Next, the operation of this embodiment will be explained.

FIGS. 2(a) to 2(c) are waveform diagrams showing the relationship between the signal waveform of the embodiment shown in FIG. 1 and the displacement of the flight hammer 4 and the tip of the piezoelectric element 3 over time.

First, when the print gate signal SC is output, the transistor Q1 of the switching element is turned on, and a current Ic flows from the power supply VCC through the resistor R2 to charge the piezoelectric element 3.
Drive voltage V applied to the piezoelectric element 3. gradually increases. Then, the piezoelectric element 3 gradually expands, and this expansion force begins to drive the flight hammer 4 that was in contact with the tip of the piezoelectric element 3. As the driving voltage vc rises, the elongation of the piezoelectric element 3 increases, and the tip of the piezoelectric element 3 and the flight hammer 4 accelerate together, and at the point P where the speed reaches the maximum, the flight hammer 4 leaves the piezoelectric element 3. fly

After that, the printing wire 41 provided on the flight hammer 4
collides with the platen 7 via the ink ribbon 5 and printing paper 6 to print dots.

Then, at the timing when the flight hammer 4 returns to the piezoelectric element 3, that is, after a certain period of time f has elapsed from the rise of the print gate signal VC, a discharge gate signal is output to turn on the switching element transistor Q2, and the piezoelectric element 3 The charges accumulated in the resistor R2 are discharged through the resistor R2. Then, the piezoelectric element 3 begins to contract, and the flight hammer 4 collides with it at point Q while the displacement of its tip is decreasing.

Therefore, since the relative speed between the piezoelectric element 3 and the flight hammer 4 at this time can be reduced, the bounce of the flight hammer 4 is reduced and the flight hammer 4 is quickly stabilized.

As a result, the time required to start the next printing operation can be shortened, and printing can be performed faster.

In addition, the printing game ■, the discharge game from the rise of the signal ■c),
Signal V (time 1 until + is output and piezoelectric element 3
The value of the resistor ζ4, which determines the discharge time constant of V), can be determined to an optimum value through simulations, experiments, etc.

〔Effect of the invention〕

As explained above, the present invention discharges the charge accumulated in the piezoelectric element at the timing when the flight hammer returns to its original position, thereby reducing the relative speed when the fly l-hammer collides with the piezoelectric element. Since the bounce of the flight hammer is reduced and it settles down quickly, the time required to start the next printing operation can be shortened and printing speed can be increased.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2(a)
~(c) is a waveform diagram showing the relationship between the signal waveform of the embodiment shown in FIG. 1 and the displacement of the flight hammer and the tip of the piezoelectric element over time, and FIG. 3 is an operation of an example of a conventional printing hammer drive circuit. FIG. 4 is a waveform diagram showing the relationship between the signal waveform of the conventional example shown in FIG. 3 and the displacement of the flight hammer and the tip of the piezoelectric element over time. 1.1a...gate signal generation circuit, 2,2. ... Switch circuit, 3... Piezoelectric element, 4... Fly I/hammer, 5... Ink ribbon, 6... Printing paper, 7...
...Platen, 41... Printing wire, 42... Leaf spring, Ql, Q2... Switch element, R,, R2...
resistance. ◆ 7th ■ He Dou Ox 3 Concave Y Go Y Mu (ms) Cow 4 Mouth

Claims (1)

[Claims] A gate that outputs a printing gate signal for selectively driving a plurality of flight hammers according to a dot matrix character pattern and a discharge gate signal generated when the driven flight hammer returns to its original position. a signal generation circuit; a plurality of switch circuits that output a drive voltage by making a first switch element conductive in response to the print gate signal; and forming a discharge circuit by making a second switch element conductive in response to the discharge gate signal; A plurality of units that generate an extension force by a driving voltage to drive the flight hammer, discharge the accumulated charge by the discharge circuit, perform a contraction operation, and reduce the impact force when the flight hammer returns to its original position. A printing hammer drive circuit characterized by having a piezoelectric element.